1. Field
This invention pertains to pump shotguns, and is specifically directed to an improved means for mounting the forearm with respect to the magazine tubes of such shotguns.
2. State of the Art
Many styles and types of pump shotguns are in use. Although a variety of mechanisms have evolved, in general all pump shotguns include a tubular magazine in which shotgun shells are stored below the barrel of the gun and forward of the receiver. The mechanism for sequentially removing shells from storage and loading them into the chamber is actuated by reciprocal motion of a forearm mounted to slide axially with respect to a magazine tube. Commonly, the forearm carries a forearm mount tube which fits concentrically around the magazine tube to facilitate smooth reciprocal motion while strengthening the forearm itself. The forearm is typically constructed of wood and/or plastic and generally fits below the magazine tube with upstanding segments straddling the magazine tube and sometimes a portion of the barrel.
The normal operation of a pump shotgun involves drawing the forearm back toward the receiver to withdraw a shell from the magazine, simultaneously ejecting a spent shell from the receiver if the gun has previously been fired. As the forearm is moved forward away from the receiver, the shell withdrawn from the magazine is loaded into the chamber in battery position for firing. A difficulty common to all existing pump shotguns is the tendency of the forearm to twist with respect to the magazine tube. That is, the forearm may rotate with respect to the magazine tube to a greater extent at one end than at its other end, thereby causing a distortion of the desired concentric orientation of the mount tube with respect to the magazine tube. As a consequence, the action of the forearm is impeded by binding of these two members. The resulting rough action is annoying and often interferes with accurate marksmanship.